High temperature, high strength alloy



Dec. 31, 1957 R. L. PETTIBONE 2,818,331

HIGH TEMPERATURE, HIGH STRENGTH ALLOY Original Filed Aug. 6, 1953 2 Sheets-Sheet 1 PLOT 0F AVERAGE WEIGHT QQIN .024 DUE r0 OX/O/IT/ON veesufi TIME nr 1000":

llllllllll'lllllll a0 /00 I20 /40 /e0 HOUES Fig.1

lllllllllllllllllll HIGH CONTENT COBHL T T/ TflN/UM flL'LO Y GAIN IN WE/GH T- 624M PER SOUfiEE INCH .040 HIGH co/vre/vr COBALT .020 TITAN/0M nuov L|||l'|||||l||1||| 20 40 G0 80 /00 I20 I40 I60 HOUES Fig.2

PtOT 0 AVE'EAGE WEIGHT Gfl/N DUE TO OXIDATION I/EQSUS TIME 47 /800 "F.

lIlllllllllllllllllllllll GAIN /!V WE/GH 7'- 620114 PE? $00405 INCH INVENTOR.

ROBERT L. PETTIBONE ATTORNEYS Dec. 31, 1957 R. PETTIBONE 2,818,331

HIGH TEMPERATURE, HIGH STRENGTH ALLOY 2 Sheets-Sheet 2 Original Filed Aug. 6, 1953 sTeEss-eupruee 0474 AT /500 "1:.

HIGH CONTENT cos/Mr TITAN/UM AL L 0 Y 0 I l l l TIME- #0025 Fig. 3

sreesseu rues om-e Ar I800'F- $8 u w 0 3 R /0,000

HIGH CONTENT c054 TITAN/UM ALLOY 0 l l I l o o./ /.0 10 I00 maa TIME H0025 INVENTOR.

ROBERT L. PE TTIBONE ATTORNEYS United States Paten HIGH TEMPERATURE, HIGH STRENGTH ALLOY Robert L. Pettibone, Grosse Ile, Mich., assignor to Eaton Manufacturing Company, Cleveland, Ohio, at corporation of Ohio Continuation of application Serial No. 372,668, August 6, 1953. This application October 22, 1956, Serial No. 617,319

2 Claims. (Cl. 75-134) This invention relates to alloys and more particularly to high temperature, high strength titanium alloys and constitutes a continuation of application abandoned Serial No. 372,668, filed August 6, 1953.

Although an extensive amount of money and time has been expended in the quest of a reasonably economical alloy for use in the fabrication of turbine buckets and the like capable of withstanding elevated temperatures for prolonged periods of time while being resistant to oxidation and capable of maintaining high strength, no alloy prior hereto has been known to fulfill the necessary requirements.

Broadly, the invention comprehends the provision of alloys having a high content of titanium and cobalt that have high temperature, high strength characteristics and that are economical as compared to previous alloys for like application such as to turbine buckets wherein resistance to high temperature and oxidation is essentially necessary.

Among the principal objects of the invention is the provision of high content cobalt-titanium alloys, that;

a. Are reasonably economical;

b. Can be easily produced such as by powder metallurgy techniques;

0. Have excellent properties at elevated temperatures;

d. Have excellent stress-rupture characteristics at high temperatures for prolonged periods of time and good resistance to oxidation at said high temperatures;

e. Provide for the production of articles therefrom having good ductility;

1. Have low density thus making them very suitable for high speed rotation such as for use as turbine buckets in jet engines; and

g. Have excellent corrosion resistance to salts, etc. in atmosphere.

Other objects and advantages of the invention will appear from the following description taken in connection with the drawings forming a part of the specification; and in which:

Figure 1 is a weight gain due to oxidation curve of a high content cobalt-titanium alloy at 1500 F.

Figure 2 is a weight gain due to oxidation curve of a high content cobalt-titanium alloy at 1800 F.

Figure 3 is a stress-rupture curve of a high content cobalt-titanium alloy at 15 F.; and

Figure 4 is a stress-rupture curve of a high content cobalt-titanium alloy at 1800 F.

The high content cobalt-titanium alloys defined hereinafter were devised primarily for use in the production of turbine blades or buckets for gas turbine jet engines and as such possess high strength at elevated temperatures capable of withstanding the operative conditions to which subjected. Furthermore, through known methods of fabrication, such as powder metallurgy, it is possible "ice to easily and economically produce alloys of this type whereby economical end products are possible, possessing better properties than alloys previously used in the production of turbine blades or buckets.

The high content cobalt-titanium alloys having the desired high temperature, high strength characteristics come within the following range of analysis, by weight:

Percent Cobalt 21-23 Titanium 31-33 Chromium 14-16 Carbon 16-18 Nickel 9-11 Tungsten 3-5 One example of a precise analysis, by weight, of the above high content cobalt-titanium alloys is as follows:

The aforesaid specifically defined alloy has a density ranging substantially between 6.2 and 6.35 grams per cubic centimeter, thus making the alloy suitable for use in the manufacture of turbine buckets of jet engines or other elements to be subjected to high speed operation, thus this alloy not only has the necessary qualities of good ductility, excellent corrosion resistance, excellent oxidation resistance and capable of maintaining its high strength at high temperature, but when combined with low weight provides one of the most suitable alloys ever developed for turbine bucket use.

Figures 1 and 2 are curves showing the average weight gain due to oxidation of high content cobalt-titanium alloys subject to the respective temperatures of 1500 F. and 1800 F. The weight gain is computed in grams per square inch of alloy for a period of time in hours to which the alloy is subjected to a predetermined oxidizing atmosphere.

Figures 3 and 4 are stress-rupture curves of high content cobalt-titanium alloys wherein the alloys are subjected to the respective temperatures of 1500 F. and 1800" F. The stress is computed in pounds per square inch as against time to fail in hours.

Whereas the curves of Figures 1 and 2 represent the fact that the high content cobalt-titanium alloys covered hereby have excellent oxidation resistance as compared to other alloys for a like use such as turbine blades, the curves of Figures 3 and 4 represent that the high content cobalt-titanium alloys covered hereby have higher stressrupture values than alloys heretofore developed and used for turbine buckets or the like.

One method of producing articles of the aforesaid high content cobalt-titanium alloys is by powder metallurgy techniques, wherein a titanium carbide skeleton or p rous body is infiltrated with an infiltrant having the proper constituent metals, whereby the end product will have the proper alloy analysis. It is conceivable that the alloys defined hereby can or will be capable of production by other methods and accordingly it is the alloy analysis herein sought to be covered rather than method of production thereof, as evidenced by the appended claims,

WhatIclaim is: 17% carbon, 15% chromium, 4% tungsten and 22% 1. A high temperature, high strength alloy consisting cobalt. of, by weight, 9-11 nickel, 31-33% titanium, 16-18%, carbon, 14-16% chromium, 3-5 tungsten and 21-23% References Clted m the file of thls patant cobalt, 5 UNITED STATES PATENTS 2. A high temperature, high strength alloy containing, 1,992,372 Hobzborger Feb. 26, 1935 by weight, approximately 10% nickel, 32% titanium, 2,752,666 Goetzel July 12, 1954 

1. A HIGH TEMPERATURE, HIGH STRENGTH ALLOY CONSISTING OF, BY WEIGHT, 9-11% NICKEL, 31-33% TITANIUM, 16-18% CARBON, 14-16% CHROMIUM, 3-5% TUNGSTEN AND 21-23% COBALT. 